We conducted a critical review of hypopigmented mycosis fungoides in historical perspective with emphasis on criteria clinical and histopathologic for diagnosis of that lymphoma as they are set forth in every article ever written about it. Toward that end, we undertook analysis of each article in the medical literature that mentioned hypopigmentation in mycosis fungoides (34 in toto). Each was scrutinized regarding content, photographs of lesions clinical pictured, and photomicrographs. On the basis of all the information in the 34 publications available to us, we made a determination about which patients had mycosis fungoides without doubt, which surely did not, and which about whom no judgment could be made by us because too little data requisite for such a decision was provided, especially in terms of photographs of lesions clinical and of photomicrographs. To date, 106 patients with "hypopigmented mycosis fungoides" have been reported on. Features clinical and findings histopathologic in 23 of those 106 patients were sufficient to permit us to determine, with a high degree of confidence, whether or not a particular patient truly had mycosis fungoides. In our judgment, 19 patients did have mycosis fungoides, whereas at least four patients did not. In regard to the other 83 patients, the information provided by the authors simply was not sufficient to allow us to come to a decision that we could justify.